Chapter 8
River engineering
8.1 Introduction
The subject of river engineering is a very wide-ranging one, and only some
of the more important aspects can be covered in this book. Other chapters
deal with structures which are usually regarded as an integral part of river
engineering, but which (in the authors’ view) have merited separate chap-
ters: diversion works, including intakes (Chapter 9); cross drainage and
drop structures (Chapter 10); inland navigation (Chapter 11). Thus only
the methods of hydrometry, i.e. the measurement of water and bed levels,
discharges and water quality, with their associated structures, as well as
river improvement structures, i.e. structures mainly designed to create
favourable geometric and kinematic conditions and/or to protect river
banks, or to aid navigation and flood control, are briefly discussed in this
chapter.
As this is also the introductory chapter to the whole subject of river
engineering (as outlined above), some basic principles of open-channel
flow and a brief discussion of river morphology and régime and of flood
routing are also included in the next sections.
The main reason for the complexity of river engineering is that river
flow in alluvium has no really fixed boundaries and geometry compared
with, say, pipe flow or open-channel flow in rigid canals. Adding to this the
complexity introduced by the changing boundary roughness in sediment-
transporting streams, and the dependence of the flow on water and sedi-
ment discharge and sediment availability, the difficulties of a rigorous
treatment of the hydraulics of flow in alluvium are increased manifold. It is
therefore hardly surprising that, despite a very substantial and sustained
research effort, our knowledge in the field of sediment transport and river
morphology is still somewhat sketchy. Nevertheless, the growing data
bank together with the application of physical principles and computer-
aided analysis are steadily advancing our ability to handle design problems